Holder Block for Both Radial and Conical Tool Picks

ABSTRACT

A holder block and pick assembly including a pick, a washer, and a block body. The pick includes a shoulder and a shank extending rearwardly from the shoulder and having a diameter smaller than the diameter of the shoulder. The washer has a central opening adapted to fit about the shank adjacent to the shoulder and a substantially flat edge disposed substantially perpendicular to a radius of the central opening. The block body includes a bore for receiving the shank, a base surface at a lower end of the body for mounting the body to a rotatable element of a rotary cutting machine, and a stop extending frontwardly from the front face of the body and having a surface located substantially perpendicularly to a radius of the bore such that when the pick shank is inserted into the bore with the washer disposed about the shank adjacent to the shoulder, the flat edge of the washer engages the surface of the stop to substantially prevent the washer from rotating with respect to the block.

FIELD

The present disclosure relates to a holder block for holding a cuttingtool pick in a rotary cutting machine, and assemblies of a holder blockwith a cutting pick. More particularly, the present disclosure relatesto a holder block adapted for interchangeably holding either anon-rotating radial pick or a rotating conical pick, and assemblies of aradial pick and a conical pick with the holder block. The disclosurealso relates to a machine incorporating such a holder block and to amethod using such a holder block and assemblies in a machine,particularly in a machine for mining, excavating, tunneling, roadplanning, and/or construction.

BACKGROUND

In the discussion of the background that follows, reference is made tocertain structures and/or methods. However, the following referencesshould not be construed as an admission that these structures and/ormethods constitute prior art. Applicant expressly reserves the right todemonstrate that such structures and/or methods do not qualify as priorart.

Two types of picks are commonly used in rotary cutting tools andmachines: a radial pick and a conical pick. Each type of pick requires adifferent mounting arrangement to optimally perform its job. A radialpick has a unidirectional cutting head designed to always face the sameorientation with respect to the target material, and functions like arake. Therefore, a radial pick must be mounted so as to be non-rotatingwithin its mounting block. A common radial pick mounting block is shownFIG. 1. The shape of the bore through the radial pick mounting block isgenerally rectangular to correspond to a generally rectangular shank ona common radial pick. A machine incorporating a plurality of radialpicks mounted on a rotating drug most effective at cutting throughsofter materials such as soil, coal, and potash.

In contrast, a conical pick has a radially symmetric cutting head thatperforms the same in any cutting direction, and functions like ascraper. Therefore, to maximize the wear life and performance of aconical pick, the pick is mounted so that it can freely rotate withinits mounting block. A common conical pick mounting block is shown inFIG. 2. The shape of the bore through the conical pick mounting block isgenerally circular to correspond to a generally circular shank on acommon conical pick. A sleeve retainer may be provided between the shankand the bore in a conical pick arrangement to reduce wear of the blockbore and to ensure a snug fit of the shank in the bore. A washer may beprovided between the shoulder of the conical pick and the face of theblock to decrease wear on the block and also to compress the sleeveretainer during installation of the sleeve retainer and pick into theblock. In some designs, the washer is non-rotating. A machineincorporating a plurality of conical picks mounted on a rotating drum ismost effective at grinding into harder, less compressive rock.

Very frequently an excavator encounters a situation in which the surfacelayers of earth are composed of softer soil-like materials that are bestdug or cut into using a radial tool machine, while lower layers of earthare composed of harder rock-like materials that are best dug or cut intousing a conical tool machine. For example, in excavating the foundationfor a dam, which must be anchored in bedrock, soil-like materials mustfirst be removed to expose the bedrock and then bedrock must be removedto create a foundation for the dam. As can be seen from FIGS. 1 and 2, atypically radial pick cannot be installed into a typically conical pickmounting block, and a typical conical pick cannot be installed into atypical radial pick mounting block. For that reason, dedicated drums areassembled for use with a rotary cutting tool machine, each drum havingeither radial pick blocks or conical pick blocks.

As a result, to change between radial picks and conical picks, theentire rotating drum of the machine must be changed. In a situation suchas the excavation described above, an excavator either must use animproper cutting system for one or the other phase of excavation (i.e.,a radial pick system for cutting rock or a conical pick system forrutting soft earth) or must endure substantial downtime in order toconvert from one cutting system to another. Changing drums on a rotarycutting machine is very time consuming and can take a machine out ofservice for three days or more, including a day or more to extract themachine from its work location to a location in which the drum can beremoved and replaced, a day or more to replace the drum, and a day ormore to put the machine back into service.

SUMMARY

An exemplary holder block for both radial and conical tool picksincludes a body having a bore for receiving a shank of a pick, the boreextending rearwardly from a front face of the body and having asubstantially circular cross-sectional shape. The holder block furtherincludes a base surface at a lower end of the body for mounting the bodyto a rotatable element of a rotary cutting machine, and a stop extendingfrontwardly from the front face of the body. The stop has a surfacelocated substantially perpendicularly to a radius of the bore at adistance from the center of the bore, the stop being adapted to engage asubstantially flat edge of a washer included in a pick assembly.

An exemplary holder block and pick assebmly includes a pick including ashoulder, a shank extending rearwardly from the shoulder and having adiameter smaller than the diameter of the shoulder, and a cutting headextending frontwardly from the shoulder. The assembly further includes awasher having a central opening adapted to fit about the shank adjacentto the shoulder, the washer having a substantially flat edge disposedsubstantially perpendicular to a radius of the central opening at adistance from the center of the central opening. The assembly alsoincludes a block body having a bore for receiving the shank of the pick,the bore extending rearwardly from a front face of the body and having asubstantially circular cross-sectional shape, a base surface at a lowerend of the body for mounting the body to a rotatable element of a rotarycutting machine, and a stop extending frontwardly from the front face ofthe body. The stop has a surface located substantially perpendicularlyto a radius of the bore at a distance from the center of the bore suchthat when the pick shank is inserted into the bore with the washerdisposed about the shank adjacent to the shoulder, the flat edge of thewasher engages the surface of the stop to substantially prevent thewasher from rotating with respect to the block. When the pick is aradial pick having, the washer integrally formed with the shoulder ofthe radial pick, the radial pick is substantially prevented fromrotating with respect to the block. When the pick is a conical pick freeto rotate with respect to the washer, the shank of the conical pick isfree to rotate is free to rotate with respect to the block while thewasher is substantially prevented from rotating with respect to theblock.

An exemplary machine for mining, excavating, tunneling, road planning,and/or construction includes a rotatable element and an exemplary holderblock and pick assembly, as set forth above, mounted to the rotatableelement.

An exemplary method of excavating uses a rotary cutting machineincluding a rotatable element having mounted thereto a holder blockincluding a bore for receiving a shank of a pick, the bore extendingrearwardly from a front face of the body and having a substantiallycircular cross-sectional shape. The holder block further includes a basesurface at a lower end of the body for mounting the body to therotatable element, and a stop extending frontwardly from the front faceof the body. The stop has a surface located substantiallyperpendicularly to a radius of the bore at a distance from the center ofthe bore, the stop being adapted to engage a substantially flat edge ofa washer included in a pick assembly. The method includes installing afirst pick into the holder block by inserting a shank of the first pickinto the bore, the first pick being one of a radial pick having a washerintegrally formed therewith and a conical pick having a washerpositioned to freely rotate with respect to the pick shank, the washerhaving an edge positioned to engage the surface of the stop such thatthe washer is substantially prevented from rotating with respect to theblock; causing the rotatable element, to rotate to enable the first pickto perform a digging or cutting action; causing the rotatable element tostop rotating; removing the first pick from the bore of the holderblock; installing a second pick into the holder block by inserting ashank of the second pick into the bore, the pick being the other of aradial pick having a washer integrally formed therewith and a conicalpick having a washer positioned to freely rotate with respect to thepick shank, the washer having an edge positioned to engage the surfaceof the stop such that the washer is substantially prevented fromrotating with respect to the block; and causing the rotatable element torotate to enable the second pick to perform a digging or cutting action.

An exemplary holder block for both radial and conical tool picksincludes a body, a base surface, and a stop. The body has a bore forreceiving a shank of a pick, the bore extending rearwardly from a frontface of the body and having a substantially circular cross-sectionalshape. The base surface is located at a lower end of the body formounting the body to a rotatable element of a rotary cutting machine.The stop extends frontwardly from the front face of the body, the stophaving a surface located substantially perpendicularly to a radius ofthe bore at a distance from the center of the bore. A radial pickinserted into the bore of the block body is substantially prevented fromrotating with respect to the block by a washer integrally formed with ashoulder of the radial pick, the washer having a flat edge adapted toengage the surface of the stop. A conical pick inserted into the bore ofthe block is free to rotate with respect to the block about an axis ofthe shank of the conical pick, while a washer disposed about the shankof the conical pick adjacent to a shoulder of the conical pick issubstantially prevented from rotating with respect to the block, thewasher having a flat edge adapted to engage the surface of the stop.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWING

The following detailed description can be read in connection with theaccompanying drawings in which like numerals designate like elements andin which:

FIG. 1 is a perspective view of a prior art radial pick mounting block.

FIG. 2 is a perspective view of a prior art conical pick mounting block.

FIG. 3A is a cross-sectional view of an exemplary embodiment of a holderblock for use with a radial pick or a conical pick.

FIG. 3B is a top end view of the embodiment of a holder block of FIG.3A.

FIG. 4 is a partial cross-sectional view of an exemplary embodiment of anon-rotating radial pick mounted in the holder block of FIGS. 3A and 3B.

FIG. 5 is a partial cross-sectional view of an exemplary embodiment of arotating conical pick and non-rotating washes mounted in the holderblock of FIGS. 3A and 3B.

FIGS. 6A and 6B are a side view and a top view, respectively of theradial pick with washer of FIG. 4.

FIGS. 7A and 7B are a side view and a top view, respectively, of theconical pick and washer of FIG. 5.

FIG. 8 is a top view of a washer for incorporation into the radial pickof FIGS. 4, 6A, and 6B, and for use with the conical pick of FIGS. 5,7A, and 7B.

DETAILED DESCRIPTION

FIGS. 3A and 3B illustrate an exemplary embodiment of a holder block 10for interchangeably holding a radial pick or a conical pick. Anexemplary embodiment of a radial pick assembly 100 including the holderblock 10 and an exemplary embodiment of a radial pick 110 is shown inFIG. 4, and detailed views of the radial pick 110 are shown in FIGS. 5Aand 6B. An exemplary embodiment of a conical pick assembly 200 includingthe holder block 10 and an exemplary embodiment of a conical pick 210 isshown in FIG. 5, and detailed views of the conical pick 210 are shown inFIGS. 7A and 7B.

As illustrated, the holder block 10 has a body 12 and a bore 14extending rearwardly from a front face 16 of the block 10. The bore 14can extend completely through the body 12 to a rear face 18 of theblock, or the bore 14 can extend partially through the body 12. The bore14 can be of a single diameter or multiple diameters. In the embodimentdepicted in FIG. 3A, the bore 14 includes a step 32 separating a largerdiameter section 30 toward the front face 16 from a smaller diametersection 34 toward the rear face 18. The bore 14, including both sections30 and 34, is substantially circular in cross-section.

A base surface 26 of the holder block 10 is located at a lower side ofthe block 10, below the bore 14, and is adapted for mounting the block10 on a surface of a rotatable element, such as a drum, of a machine formining, excavating, tunneling, road planning, and/or construction.Typically, many holder blocks 10 are mounted on an outer surface of therotatable element. When the block 10 is mounted to a rotatable element,both the front face 16 and the back face 18 of the body 12 areaccessible for installation, removal, and replacement of a pick in thebore 14.

A stop 20 is located a distance D1 from the center of the bore 14. Thestop 20 extends outwardly in a frontward direction from the front face16 of the block body 12. The stop 20 having a generally flat surface 22disposed substantially perpendicularly to a radius of the bore 14. Inother words, the flat surface 22 lies in a plane that is substantiallyparallel to the centerline of the bore 14 and substantiallyperpendicular to the front face 16 of the block body 12. As depicted,the stop 20 is positioned lower on the block body 12 than the junctionbetween the bore 14 and the front face 16, so that it is disposedgenerally between the bore 14 and the rotatable element to which theblock 10 is mounted, in this arrangement, the distance between the stop20 and the base surface of the block 10 is relatively small comparedwith other possible mounting locations of the stop 20, which minimizesthe torsional loads imposed on the mounting junction between the basesurface 26 and the rotatable element of the cutting machine when loadsare applied to the stop 20 by a pick installed in the block 10.Alternatively, the stop 20 can be positioned on the block body 12 in anyradial direction with respect to the bore 14 provided the torsionalloads transmitted from the stop 20 to the mounting junction between thebase surface 26 and the rotatable element of the cuffing machine aretaken into account.

The stop 20 can be integrally formed into the body 12 of the block 10,or can be securely affixed to the body 12 by welding or otherstructurally secure mechanism. As shown in FIG. 3A, the stop 20 issecurely welded to the body 12 of the block 10 along two sides, asindicated by a weld bead 24.

The holder block 10, including the bore 14 and the stop 20, is adaptedto interchangeably accommodate a radial pick or a conical pick, asdisclosed herein. FIG. 4 shows a radial pick assembly 100 including aradial pick 110 mounted in the block 10. FIG. 5 shows a conical pickassembly 200 including a conical pick 210 mounted in the block 10.

An exemplary radial pick 110 is shown in FIGS. 5A and 6B. The radialpick 110 spans from a front end 130 to a rear end 132 and includes afrontwardly extending cutting head 116 and a rearwardly extending shank120. The out head 116 supports a unidirectional cutting tip 118. Theshank 120 is sized to fit within the bore 14 in the body 12 of theholder block 10. In the depicted embodiment, the shank 120 has a steppeddiameter, including larger diameter section 124 toward the cutting head116 and a smaller diameter section 126 away from the cutting head 116,the sections 124 and 126 being separated by a step 128, A groove 122 isprovided at the rear end 132 of the shank 120 for receiving a retainingmeans such as a C-clip (not shown).

An enlarged shoulder 114 is disposed between the cutting head 116 andthe shank 120, the shoulder 114 having an outer diameter larger thanthat of the larger diameter section 124 of the shank 120, and thereforealso larger than the inside diameter of the larger diameter section 30of the bore 14. A washer 300 integrally formed with the shoulder 114 ofthe radial pick 110 such that the washer 300 cannot rotate with respectto the radial pick 110. In one embodiment, the washer 300 is integrallyformed with the shoulder 114 by welding the washer 300 to the shoulder114. In another embodiment, the washer 300 is integrally formed with theshoulder 114 by forging the washer 300 into the shoulder 114. It isunderstood that other methods for integrally forming the washer 300 intothe shoulder 114 can alternatively be used. The radial pick 110 can beretained in the block 10 by any known retaining means. For example, inthe depicted embodiment, the shank 120 of the radial pick 110 extendsout the bore 14 beyond the rear face 18 of the block 10 and the groove122 in the shank 120 receives an external C-clip.

An exemplary washer 300 is shown in FIG. 8. The washer 300 has a centralopening 306 with an inner diameter sufficient to allow the washer 300 toslide over the shank 120 of the radial pick 110, but smaller than theouter diameter of the shoulder 114 of the radial pick 110. The washer300 has an outer D-shaped perimeter including a flat edge 302 and aremaining curved edge 304. The flat edge 302 of the washer 300 islocated at a distance D2 from the center of the central opening 306 ofthe washer 300 and is formed to be substantially perpendicular withrespect to a radius of the central opening 306. In other words, the flatedge 302 lies in a plane that is substantially parallel to thecenterline of the more central opening 306. The distance D2 isapproximately equal to or slightly less than the distance D1 from thecenter of the bore 14 of the block 12 to the surface 22 of the stop 20.

When the radial pick 110 is installed in the block 12, the shank 120 isreceived into the bore 14 and the flat edge 302 of the washer 300 islocated adjacent to, and in contact with or nearly in contact with thesurface 22 of the stop 20. The surface engagement between the flat edge302 of the washer 300 and the surface 22 of the stop 20 substantiallyprevents the radial pick 110 from rotating with respect to the block 10,so that the cutting tip 118 of the radial pick 110 is maintained in adesired cutting orientation, regardless of the forces imposed on thecutting tip 118 from contact with the material being dug or cut into bythe rotary cutting machine. The radial pick 110 can be readily removedfor replacement, if desired, by removing the retaining means, such as anexternal C-clip inserted into the groove 122, and sliding the shank 120frontwardly from the bore 14.

An exemplary conical pick 210 is shown in FIGS. 7A and 7B. The conicalpick 210 spans from a front end 230 to a rear end 232 and includes afrontwardly extending cutting head 216 and a rearwardly extending shank220. The cutting head 216 supports a radially symmetric cutting tip 218.The shank 220 is sized to fit within the bore 14 in the body 12 of theholder block 10. An enlarged shoulder 214 is disposed between thecutting head 216 and the shank 220, the shoulder 214 having an outerdiameter larger than that of the larger diameter section 124 of theshank 120 and therefore also larger than the inside diameter of thelarger diameter section 30 of the bore 14.

In the depicted embodiment, the shank 220 has a smaller diameter section226 away from the cutting head 216 corresponding to the smaller diametersection 34 of the bore 14. The shank 220 further includes a reduceddiameter section 224 toward the cutting head 216, the reduced diametersection being bounded by a shoulder 228 located between the reduceddiameter section 224 and the smaller diameter section 226 and a shoulder229 located between the reduced diameter section 224 and the enlargedshoulder 214. The shoulders 228 and 229 each have an outer diametersized to fit in the larger diameter section 30 of the bore, and thereduced diameter section 224 has an outer diameter smaller than that ofthe shoulders 228 and 229. The reduced diameter section 224 is adaptedfor receiving a sleeve retainer 240. A groove 222 is provided at therear end 232 of the shank 220 for receiving a retaining means such as aC-clip (riot shown).

The sleeve retainer 240 can be any suitable generally cylindrical hollowsleeve retainer having a longitudinal slit 242 to allow for radialcompression of the sleeve retainer 240 against its own spring force.When the conical pick 210 with the sleeve retainer 240 is installed inthe bore 14, the spring force of the sleeve retainer 240 presses sleeveretainer 240 against the inner surface of the bore 14 so that the sleeveretainer 240 remains substantially non-rotating with respect to the bore14, while the shank 220, and thus the conical pick 210, is permitted torotate freely within the sleeve retainer 240 and within the bore 14. Asthe cutting tip 218 contacts the material being dug or cut into, theconical pick 210 can freely rotate, providing for uniform wear andcontinual sharpening of the cutting tip 218. In addition the sleeveretainer 240 protects the bore 14 of the block 12 from wear due to therotation of the shank 220.

When the sleeve retainer 240 is compressed within the bore 14, thesleeve retainer 240 is held captive around the reduced diameter section224 of the shank 220 by the shoulders 228 and 229, so that the sleeveretainer 240 cannot move in an axial direction with respect to the pick220. The frictional engagement between the sleeve retainer 240 and thebore 14, combined with the engagement between the sleeve retainer 240and the shoulder 228, helps to retain the conical pick 210 within thebore 14. Alternatively, or in addition to the retention force providedby the sleeve retainer 240, the shaft 220 of the conical pick 210extends out the bore 14 beyond the rear face 18 of the block 10 and thegroove 222 in the shank 220 receives an external C-clip.

The washer 300 serves multiple purposes when used with the conical pick210. As shown in FIG. 7A, the washer 300 is used to radially compressthe sleeve retainer 240 to enable the shank 220 with the sleeve retainer240 to be inserted into the bore 14. In addition, the washer 300protects the front face 16 of the mounting block 10 from wear by a rearface 212 of the shoulder 214 as the conical pick 210 rotates during use.

When the conical pick 210 is fully installed into the bore 14 of theblock 10, the washer 300 is in contact on one side with the rear face212 of the shoulder 214 and on the other side with the front face 16 ofthe block 10. In this position, the central opening 306 of the washer300 is disposed about the shoulder 229 of the shank 220 frontward of thelocation of the sleeve retainer 240, so that the sleeve retainer 240 isfree to spring radially outward against the inside of the bore 14.

To most effectively protect the front face 16 of the block 10 from weardue to rotation of the shoulder 214 of the conical pick 210, the washer300 is held stationary by the same mechanism that holds the rotary pick110 stationary when a rotary pick 110 is used. In particular, the fiatedge 302 of the washer 300 engages the surface 22 of the stop 20 tosubstantially prevent the washer 300 from rotating. Because the washer300 is merely disposed about the shank 220 and is not affixed to theshoulder 214, in contrast to the arrangement of the radial pick 110, theconical pick 220 is free to rotate within the bore 14 while the washer300 remains substantially non-rotating.

Although described in connection with preferred embodiments thereof, itwill be appreciated by those skilled in the art that additions,deletions, modifications, and substitutions not specifically describedmay be made without department from the spirit and scope of theinvention as defined in the appended claims.

1. A holder block for both radial and conical tool picks, the blockcomprising: a body having a bore for receiving a shank of a pick, thebore extending rearwardly from a front face of the body and having asubstantially circular cross-sectional shape; a base surface at a lowerend of the body for mounting the body to a rotatable element of a rotarycutting machine; and a stop extending frontwardly from the front face ofthe body, the stop having a surface located substantiallyperpendicularly to a radius of the bore at a distance from the center ofthe bore, the stop being adapted to engage a substantially flat edge ofa washer included in a pick assembly.
 2. The holder block of claim 1,wherein the pick assembly includes a radial pick having a washerintegrally formed therewith, the washer having an edge positioned toengage the surface of the stop when the pick shank is installed in thebore such that the radial pick is substantially prevented from rotatingwith respect to the block.
 3. The holder block of claim 2, wherein thewasher is integrally formed with the radial pick by forging.
 4. Theholder block of claim 2 wherein the washer is integrally formed with theradial pick by welding.
 5. The holder block of claim 1, wherein the pickassembly includes a conical pick having a washer rotatably disposedabout the pick shank between a shoulder of the pick and the front faceof the body, the washer having an edge positioned to engage the surf acof the stop when the pick shank is installed in the bore such that theconical pick can freely rotate with respect to the block while thewasher is prevented from rotating with respect to the block.
 6. Theholder block of claim 1, wherein the stop is orated lower on the bodythan a junction between the bore and the front face of the body.
 7. Aholder block and pick assembly comprising: a pick including a shoulder,a shank extending rearwardly from the shoulder and having a diametersmaller than the diameter of the shoulder, and a cutting head extendingfrontwardly from the shoulder; a washer having a central opening adaptedto fit about the shank adjacent to the shoulder, the washer havingsubstantially flat edge disposed substantially perpendicular to a radiusof the central opening at a distance from the center of the centralopening; and a block body having: a bore for receiving the shank of thepick, the bore extending rearwardly from a front face of the body andhaving a substantially circular cross-sectional shape; a base surface ata lower end of the body for mounting the body to a rotatable element ofa rotary cutting machine; and a stop extending frontwardly from thefront face of the body, the stop having a surface located substantiallyperpendicularly to a radius of the bore at a distance from the center ofthe bore such that when the pick shank is inserted into the bore withthe washer disposed about the shank adjacent to the shoulder, the flatedge of the washer engages the surface of the stop to substantiallyprevent the washer from rotating with respect to the block; wherein whenthe pick is a radial pick having the washer integrally formed with theshoulder of the radial pick, the radial pick is substantially preventedfrom rotating with respect to the block; and wherein when the pick is aconical pick free to rotate with respect to the washer, the shank of theconical pick is free to rotate is free to rotate with respect to theblock while the washer is substantially prevented from rotating withrespect to the block.
 8. The assembly of claim 7, we rein the stop islocated lower on the body than a junction between the bore and the frontface of the body.
 9. A machine for mining, excavating, tunneling, roadplanning, and/or construction comprising: a rotatable element; and theassembly as in claim 7 mounted on the rotatable element.
 10. A method ofexcavating using a rotary cutting machine, including a rotatable elementand a holder block as in claim 1 mounted to the rotatable element, themethod comprising: installing a first pick into the holder block byinserting a shank of the first pick into the bore, the first pick beingone of a radial pick having a washer integrally formed therewith and aconical pick having a washer positioned to freely rotate with respect tothe pick shank, the washer having an edge positioned to engage thesurface of the stop such that the washer is substantially prevented fromrotating with respect to the block; causing the rotatable element torotate to enable the first pick to perform a digging or cutting action;causing the rotatable element to stop rotating; removing the first pickfrom the bore of the holder block; installing a second pick into theholder block by inserting a shank of the second pick into the bore, thesecond pick being the other of a radial pick having a washer integrallyformed therewith and a conical pick having a washer positioned to freelyrotate with respect to the pick shank, the washer having an edgepositioned to engage the surface of the stop such that the washer issubstantially prevented from rotating with respect to the block; andcausing the rotatable element to rotate to enable the second pick toperform a digging cutting action.
 11. A holder block for both radial andconical tool picks, the block comprising: a body having a bore forreceiving a shank of a pick, the bore extending rearwardly from a frontface of the body and having a substantially circular cross-sectionalshape; a base surface at a lower end of the body for mounting the body arotatable element of a rotary cutting machine; and a stop extendingfrontwardly from the front face of the body, the stop having a surfacelocated substantially perpendicularly to a radius of the bore at adistance from the center of the bore; wherein a radial pick insertedinto the bore of the block body is substantially prevented from rotatingwith respect to the block by a washer integrally formed with a shoulderof the radial pick, the washer having a flat edge adapted to engage thesurface of the stop; and wherein a conical pick inserted into the boreof the block is free to rotate with respect to the block about an axisof the shank of the conical pick, while a washer disposed about theshank of the conical pick adjacent to a shoulder of the conical pick issubstantially prevented from rotating with respect to the block, thewasher having a flat edge adapted to engage the surface of the stop.